This invention relates generally to drive mechanisms and more particularly to an axial drive mechanism that has the advantage of being compact and can thus be used in installations, such as adjustable seat mechanisms, where space availabilities limit the size and shape of the drive mechanism that can be used. The drive mechanism is conveniently driven by an electric motor with a coaxial drive shaft but it can also be driven by a remote drive.
The axial drive assembly of this invention includes a worm gear, a planetary gear system having a carrier, helical planet gears mounted in inclined positions on the carrier in meshing engagement with the worm gear, and a ring gear which is formed integral with the carrier, the planetary gear system being in a coaxial relation with the worm gear. The ring gear can then be used to drive a variety of other mechanisms.
A second planetary gear system having planet spur gears arranged about and in meshing engagement with the first ring gear can be disposed in axial alignment with the first planetary gear system to obtain a further gear reduction. The second planetary gear system includes a stationary ring gear which encircles the planet spur gears and is integrally formed with the housing for the drive assembly. The second planetary gear system also includes a carrier on which the planet spur gears are mounted and an output pinion gear that is formed integral with the last mentioned carrier.
The drive shaft, worm gear, carriers and ring gears are in substantial axial alignment to thereby confine the transverse dimension of the drive assembly. In one embodiment of the invention, this dimension is substantially the same dimension as the transverse dimension of an electric motor used to drive the worm gear.
It can thus be seen that in the drive mechanism of this invention, the two planetary gear systems are structured and arranged so that they are coaxial with each other and with the worm gear and operate to provide an output which is of reduced speed and of increased torque relative to the output from the electric motor drive shaft. Such a drive assembly has applicability to numerous mechanical environments wherein components must be selectively moved.